A sampler is a device which
allows you to map any sound to a musical keyboard,
and is a very popular in modern music making. An
instrument can be very basic with a single sample
stretched across the octave ranges, or a complex
multi-sampled instrument which attempts recreate
an acoustic instrument such as a piano. If you remember
The Art of Noise they used an early very expensive
sampler called a Fairlight to make all of their
records, notably the vocal samples (Dum).

A software sampler is a program
which runs on a computer which emulates a hardware sampler. In the past
this was impossible as the processing power to do this was too great,
people had samplers built on to soundcards (such as soundfonts),
which didn't rely on CPU leaving it free for other tasks. However in recent
times computers have become considerably less expensive and more powerful,
and a software sampler can run very easily.

The first major contender
was Gigasampler which still has a large following and a huge sample library
available. More recently the focus has been on soft samplers which plug
in to sequencers and fit in to the environment which you work in. Examples
of these are Emagic EXS24, Steinberg HALion, Native Instruments Kontakt,
and Speedsoft Virtual Sampler.4
What is a hardware Sampler? top

There are many hardware samplers
out there notably made by AKAI, Roland, Yamaha and
Kurzweil. They are expensive to buy compared to
software samplers, however they are extremely reliably
and you do not have to deal with computer problem
when using them!5.
Where do I get sampled instruments from? top

There are many sample CDs available from places
like Time and Space, and of course the Homegrown
Sounds range of CDs :)There are also places
on the internet to buy individual instruments which
you download immediately such as http://www.dashsounds.com